62 GEORGE C. WHIPPLE 



In Fuertes' book on Water and the Public Health a diagram is 

 given showing that the typhoid fever death-rates in cities supplied 

 with ground water vary from 5 to 32 per 100,000 in America, and from 

 6 to 33 per 100,000 in Europe, the average being about 18 in America 

 and 19 in Europe. It is shown also that the death-rates from cities 

 supplied with filtered water vary from 4 to 20 in America, and from 

 4 to 20 in Europe, the average being 12 in both cases. Recent Ameri- 

 can data for cities supplied with filtered water show that the rates are 

 somewhat higher than these, the average being somewhat less than 20. 



Taking into consideration the best available data, it seems reason- 

 able to place the general value of N somewhere between 10 and 25 

 per 100,000, with the most probable average value as 20, which figure 

 may be used in the equation where local sanitary conditions are 

 unknown. The value of AT, however, should be varied where there is 

 reason for doing so. Where the sanitary conditions are good 15 may 

 be taken as a fair value. In New England it might be placed lower 

 than in regions south of the glacial drift ; in cities near the seaboard, 

 where there is a large consumption of oysters consumed fresh from 

 the layings, the value of N might be higher than in inland cities, 

 where the oyster consumption is small and where fattened oysters are 

 not used as freely ; in cities where there are cess-pools, but no sewers, 

 the value of N would naturally be higher than in cities well provided 

 with sewers. 



It may be reasonably expected that, as time goes on, the value of 

 N will gradually fall, because of a general decrease of typhoid fever in 

 the country at large, and a consequent diminution of the number of 

 foci of infection. Statistics for twelve states, including all the New 

 England states, New York, New Jersey, Maryland, California, Min- 

 nesota, and Michigan, show that during the last quarter of a century 

 the general typhoid fever death-rate has fallen as follows: 



TABLE 4 



Average Typhoid 

 Fever Death- 



Rate per 

 Year 100,000 



1880 55 



1885 46 



1890 36 



1895 28 



1900 23 



1905 2I 



